Soluble benzyl ether of dextran



Patented June 11, 1940 PATENT OFFICE SOLUBLE BENZYL ETHER OF DEXTRAN Grant L. Stahly and Warner W. Carlson,

Columbus, Ohio, assignors to Commonwealth Engineering Corporation, Wilmington, Del., a corporation of Delaware No Drawing.

Application February 26, 1938,

Serial No. 192,886

2 Claims.

This invention relates to coatings such as lacquer and the like.

It is an object to provide a coating which can be applied by brushing or roller coating, but pref- 5 erably by spraying, which will be characterized by very rapid drying, a coating that is tenacious to supporting surfaces, such as that of metal, and which is substantially inert to water, to certain acids, alkalis and alcohols and other similar solvents, while it is soluble in certain cheap solvents which make it available as an industrial coating.

It is an object to provide such a coating that is soluble in acetone, cellosolve, dioxane, ethyl acetate, butyl acetate, diacetone, mesityl oxide and chloroform.

It is a further object to provide a coating that is substantially not inflammable, either. before coating or afterwards, and upon being coated when the solvent is dried or evaporated, it is substantially without infiammability.

It is a further object to provide such a lacquer coating which does not necessarily need any plasticizer or any resins in order to make it hard, impervious to attacking agents, brilliant on its surface, and substantially clear as a varnish.

Heretofore in the art the most useful of the quick drying lacquer coatings have been nitrocellulose lacquer coatings made from. low viscosity cellulose nitrate. Such a coating has been 0 revolutionary in its effect in opening up the mass production of articles in industry because of its quick drying and spreading powers.

This prior art nitrocellulose lacquer has had several serious disadvantages. The first is its in- 35 herent inflammability, not only prior to being mixed with the solvent but after having been applied to a metal or other surface and the solvent evaporated. It has the further disadvantage of necessitating expensive plasticizers and resins in order to give it satisfactory adhering power and satisfactory brilliance.

The instant'invention eliminates these disadvantages in that it will dry in approximately fifty per cent of the time now necessary for the drying of cellulose lacquers, and it is expected with further experience with the lacquer of the instant invention that its present drying time will be very materially reduced by better methods of mechanical application, This advantage is a material one in industry in that it reduces the time of drying and thereby increases proportionately the production rate of expensive labor, machinery and materials. The lacquer of this invention is further capable of being satisfactorily applied and satisfactorily adhering to such surfaces as metal without the necessity of the use of expensive plasticizers, as it is very tough and inherently brilliant so that there is no necessity for using resins. This does not mean that plasticizing resins cannot be used with it but there is no necessity as exists with the present lacquers now used in the art.

One ofthe principal objects of this invention is to provide a coating of this character that is inert to those things that normally affect an automobile body finish but which at the same time would be soluble in such cheap solvents as acetone.

It is the object of this invention to provide a lacquer made of soluble benzyl ether of dextran.

PROCESS OF PREPARATION In order to secure the lacquer of this invention,

a solution of dextran is heated with benzyl chloride and sodium hydroxide for suitable periods of time and at suitable temperatures. There results from this process either a benzyl ether of dextran which is insoluble in acetone and other similar solvents or a benzyl ether of dextran which is soluble in acetone.

It has been shown that dextran has one of the following formulas:

1 l l -n--- on n n nc J-on noon noon noon i noc-n noon noon noon n n l l l I O H O nc-on noon noon no- 0- o-o-c- -cn.on 50 I l l n n o n n no m non( n cH,-- CHrcni-- CH:----

... 0 I 111- Ln Lmcinm onl O noon n on n+onJ noon no 11 noon noon neon n on n on n He no n n I n n o n o n,- 11,- n. on,- o-- c-cccn.on

- n g. n n

It is apparent that the primary unit of the dextran molecule is a chain of four anhydroglucose residues joined uniformly by glucosidic linkages between the first and sixth carbon atoms of contiguous hexose units. According to Formula I, the fourth hexose unit carries a side chain of one anhydroglucose residue on carbon atom No. 4; according to Formula II, the side chain anhydroglucose unit is attached to the sixth carbon atom and attachment is made to the rest of the molecule through carbon atom No. 4. It is not known how many of these five anhydroglucose units there are in a molecule of dextran but the presence of the side chain separates it definitely in structure from such common polysaccharidesas starch and cellulose.

When benzyl chloride is heated with dextran in the presence of sodium hydroxide the benzyl radical is substituted for the hydrogen atom in one or more of the hydroxyl groups in the dextran molecule (see Formulas I and II). The acetone-soluble product contains more benzyl radicals in each anhydroglucose unit than does the acetone-insoluble product. The soluble product is the one described herein.

The following are typical examples of the process. It will be understood that the proportions indicated'are relative and approximate in the sense that further experience, may indicate modifications of the proportions, depending on the type of production machinery employed and other factors. Modifications of temperature, time and pressure may, likewise, be desirable.

Exsmrtr: I

135 to 145 degrees C. for four hours. Soluble benzyl dextran was obtained.

EXAMPLE II To 30 grams of dextran in 100 cc. of water were added 93 grams of benzyl chloride (mole ratio of 4:1) and 32 grams of sodium hydroxide, and the mixture refluxed with stirring for 0.5 hour at 75 to degrees C. The temperature was then raised to and held at 135 to 140 degrees C. for 0.5 hour. Again it was slowly raised so that at the end of 1.5 hours it stood' at 175 to 185 degrees C. where it was held for an additional 1.5 hours. The total heating period was three hours and the yield of soluble benzyl dextran was good.

EXAMPLE II-I Thirty grams of dextran, 100 cc. of water, 4'7 grams of benzyl chloride (mole ratio of 2:1) and 16 grams 01 sodium hydroxide were refluxed at '15 to 80 degrees C. with stirring for 0.5 hour. Then 23.5 grams of benzyl chloride (total mole ratio of 3:1) and 10 grams of sodium hydroxide were added, and the temperature raised slowly so that at the end of the first hour it stood at 1'75 .to 185 degrees 0., where it was maintained for two hours. Soluble benzyl dextran results.

Exsurrn IV Thirty grams of dextran, 82 grams of benzyl chloride (mole ratio of 35:1). and 30 grams of sodium hydroxide were heated in an iron vessel, with stirring at 25 lbs. per square inch pressure for 0.05 hour. A soluble benzyl ether of dextran is obtained.

ExAurLs V 30 gm. of dextran gm. oi. benzyl chloride 40 gm. of sodium hydroxide It is found that heating under reflux should be conducted from approximately degrees C. to degrees-C. for about six hours. This invention is not confined to such temperatures and pressures but this is a satisfactory procedure. It has been found that the addition to the foregoing Example V, after the supernatant liquid has been poured off, of a second batch of 90 grams or benzylchloride, 40 grams of sodium hydroxide,

and 200 cc. of water, and the reheating oi the materials under reflux for an additional six hours gives a desirable product. The reaction mixture is steam-distilled to recover benzyl chloride and benzyl alcohol. This is a mole ratio of 7.5:1 moles of 'benzyl chloride to dextran.

Exauru: VII

To 30 grams of dextran dissolved in 100 cc. of water were added 141 grams of benzyl chloride and 45 gramsoi sodium hydroxide, and the mixture refluxed at 105 to degrees C. for ten hours. The supernatant liquid was poured 01!, the residue well washed with cold water, and extracted with 400 cc. of acetone. The acetone extract was then poured into cold water to reprecipitate the benzyl dextran, which was then dried in the oven at 90 degrees C. Thirty-six grams of benzyl dextran, representing a yield of 59 per cent or the theoretical amount of 63 grams was obtained. The molecular ratio was 6 moles of benzyl chloride to 1 of dextran.

ExAmLE VIII To 30 grams of dextran dissolved in 100 cc. of water were added 1175 grams of benzyl chloride and 38 grams of sodium hydroxide. and the mixture refluxed for ten hours at 105 degrees to 110 degrees C. With the same purification procedure as was described before. 28 grams of benzyl dextran were obtained, a yield of 44 per cent of the theoretical. The molecular ratio of benzyl chloride to dextran in this case was 5:1.

EXAMPLE IX To 30 grams of dextran dissolved in 100 cc. of

water were added 93 grams of benzyl chloride.

and 32 grams of sodium hydroxide, and the mixture refluxed at 105 degrees to 110 degrees C. for ten hours. After the usual purification, a yield of 12 grams (19 per cent) of acetone-soluble, and 23 grams (37 per cent) of acetone-insoluble benzyl dextran were obtained. The molecular ratio of benzyl chloride to dextran was 4:1.

EXAMPLE X To 30 grams of dextran dissolved in 100 cc. of water were added 23.5 grams of benzyl chloride (mole ratio of 1:1) and 10 grams of sodium hydroxide, and the mixture heated at 105 to 110 degrees C. for six hours. At the end of this time, grams of benzyl chloride (bringing the final mole ratio to 4:1) and 25 grams of sodium hydroxide were added and heating continued at 135 to 140 degrees C. for 4 hours more. Thirty-one grams (49 per cent yield) of acetone-soluble benzyl dextran were obtained.

EXAMPLE XI To 30 grams of dextran dissolved in 100 cc. of water were added 70 grams of benzyl chloride (mole ratio of 3:1) and 25 grams of sodium hydroxide, and the mixture heated as before at 105 to 110 degrees C. for 6 hours. With the addition of 23 grams of benzyl chloride (bringing the total mole ratio to 4:1) and 10 grams of sodium hydroxide, the mixture was heated for an additional 4 hours at 135 to 140 degrees C. The yield of acetone-soluble benzyl dextran was 48 grams, or '76 per cent of the theoretical.

EXAMPLE XII To 30 grams of dextran dissolved in 100 cc. of water were added 58.75 grams of benzyl chloride (mole ratio of 25:1) and 20 grams of sodium hydroxide, and the mixture heated with stirring for 3.5 hours at to degrees C. At the end of this time, 35.3 grams of benzyl chloride (bringing the total mole ratio to 4:1) and 12 grams of sodium hydroxide were added, and heating continued at 135 to 145 degrees C. for 0.5 hour, and then at 175 to 185 degrees C. for 2 hours. The total period of heating was 6 hours.

EXAMPLE XIII To 30 grams of dextran in cc. of water were added 93 grams of benzyl chloride (mole ratio of 4:1) and 32 grams of sodium hydroxide, and the mixture heated at to degrees C. for 0.5 hour. During the next half-hour the temperature was slowly raised so that at the end of the first hour of heating it stood at to degrees C., where it was held at 175 to 185 degrees 0., giving a total heating period of 4 hours.

EXAMPLE XIV To 375 cc. of a culture medium containing 30 grams of dextran were added 47 grams of benzyl chloride (mole ratio of 2:1) and 16 grams of sodium hydroxide, and the solution heated at 75-to 80 degrees C.- for 0.5 hour with stirring. The temp rature was then. raised and held at 105 to 110 degrees C. for'one hour. Forty-seven grams ofbenzyl chloride (making the total mole ratio 4:1) and 16 grams of sodium hydroxide were added, the mixture heated at 120degrees to 125 degrees C. for 1 hour, and at to degrees C. for

three .hours.

The purification of the benzyl ether of dextran involves in general (1) steam distillation for the removal of benzyl alcohol and excess benzyl chloride, (2) maceration of the benzyl ether of dextran in water to remove water-soluble impurities and (3) complete removal of the water from the resulting product. Detailed methods of purification may vary widely according to convenience. The purpose of purification is also to recover the benzyl alcohol and excess benzyl chloride in the steam distillate.

Solvents The following is a table giving the solvent Two points of particular interest are to be noted in the table: (1) the insolubility of the benzyl dextran in water, alkalis, acids and the common alcohols, and (2) its solubility in the cheap commercial solvents, acetone, ethyl acetate and butyl acetate. By properly regulating the proportions of these solvents in the finished lacquer it is possible to obtain a wide variation in the rate of drying. It is comprehended within the term solvent or the use of the terms acetone, butyl acetate or ethyl acetate, such other equivalent solvents as may from time to time be available in this connection. Under some circumstances it is found desirable to mix with such solvents others to bring the evaporation rate to such controlled rate as may be desired, as the rate of evaporation with acetone or ethyl acetate is very high.

The proportions of solvent and benzyl ether of dextran depend upon the type of coating to be employed. It has been found that 20 per cent solids and the balance solvents is a satisfactory proportion for some types of coatings.

The dextran itself is necessarily produced bacteriologically, and the benzyl ether of dextran is therefore produced by the combined bacteriological and chemical action, as set forth in the co-pending application of Grant L. Stahly and Warner W. Carlson, Serial Nos. 156,426 and 156,427, both filed July 29, 1937. In the event oi following such methods so disclosed-then such methods are modified in accordance with this present invention.

The process and the reaction follow generally two stages: first, the production of an insoluble benzyl dextran, and secondly, the substitution of an additional hydroxyl group to yield a soluble product.

The method of producing the products recited herein is claimed in our co-pending case Ser. No. 192,887, filed Feb. 26, 1938. I

It will be understood that it is desired to comprehend within-this invention such modifications as come within the scope oi the claims and the invention.

Having thus fully described our invention. what we claim as new and desire to secure by Letters Patent, is:

class consisting of acetone, ethyl acetate and 10 butyl acetate.

GRANT L. STAHLY. WARNER W. CABISON.

, CERTIFICATE OF CORRECTION. Patent No'. 2,205,705. Y June 11, 191m.

GRANT L. STAHLY,- ET AL.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 2, second column; line 27, Example IV, for "0.05 hour" read O.5 hour--; page 5, second column, line 28', in the table, for "ZNI-ICL" read --2N HC1-;' line '29, for "ZNNaOH" read --2N NaOH-; and that the said Letters Patent should be read v vi th this correction therein 'that the same may conform to the rec- 6rd -of the case inthe Patent Office.

Signed and sealed this 11th day of November, A. e D. 19in.

- Henry Van Arsda'ie;

v (Seal) Acting Commissioner of Patents. 

